G jahn



G. JAHN W 2,184,598 DEVICE FOR THE SEPARATION OF SOLIDS OF VARIOUSPARTICLE SIZES CONTAINED Dec. 26, 1939.

IN A FLUID, ESPECIALY IN THE MANUFACTURE OF. STARCH Filed April 27, 19372 Sheets-Sheet 1 I I I M .Q M m 7% eoiy Jam Dec. 26, 1939. G JAHN I2,184598 DEVICE FOR THE SEPARATION OF SOLIDS OF VARIOUS PARTICLE SIZESCONTAINED IN A FLUID, ESPECIALY IN THE MANUFACTURE OF STARCH Filed April2'7, 1957 2 Sheets-Sheet 2 Fig:5

Geozy By r Patented Dec. 26, 1939 UNITED STATES PATENT OFFICE DEVICE FORTHE SEPARATION OF SOLIDS OF VARIOUS PARTICLE SIZES CONTAINED IN A FLUID,ESPECIALLYIN THE MANU- FACTURE OF STARCH Georg Jahn, Arnswalde, GermanyApplication April 27, 1937, Serial No. 139,322

4 In Germany April 29, 1936 7 Claims.

the narrower part of the outer drum, from the so-called inlet side, thenas a result of the centrifugal force the solid, heavy components deposit on the inner wall 'of the outer drum; Whilst the lighter partsflow to the side located opposite the inlet, ,the heavier substances arescraped off the wall of the drum by the worm device and are conveyed toan outlet, for the 20 solid substances, located at the inlet side,during which they contact with a dry zone not touched by the fluidsurface.

It has already been attempted to improve the operation of thesecentrifuges by constructing 25 the inner drum, which carries and movesthe worm device, partly as a sieve drum and conducting the coarser solidsubstances, of the fluid introduced into the interior of the sieve drum,which do not pass through the latter, to the 30 outlet for the solidsubstances by a shorter pat by means of a separately driven worm.

Since in this known improved centrifuge the finer solid substancesthrown through the sieve drum are again combined at the outlet or alittle 35 in front of this with the coarser solid substances which thesieve drum has not permitted to pass through this centrifuge, like thecentrifuge with a completely closed housing mentioned initially,

efiects separation of the solid substances only ac- 40 cording tospecific gravity, and not a separation according to: the size of theparticles. Separation in accordance with the size or nature, for exampleobstructiveness of the parts to be separated is however desired for manypurposes.

45 For example,,it is advantageous in themaking of clay into paste orslurry, if the pieces of clay are separated from one another accordingto size and are moreover separated from the water.

Such a double separation into at least three and I products couldpreviously be carried out only by on the one hand for the separation ofthe starch grains from the vegetableiluid of the initial raw materialand from their coarser fibrous constituents on the other hand, at leasttwo groups of separating apparatus, viz. in the case of modern 6processes, for example centrifugal separators on, the one hand andwashing-out apparatus on the other hand. In that case there is employedeven at best one centrifuge fed with diluted shredding of the initialmaterial and one fed with raw 10 starch milk, that is one centrifuge infront of and one following the washing-out apparatus,

in the same process.

The object of the invention is to obviate the need for such a costlyspace and time wasting accumulation and the arranging in series ofseparate separating apparatus in such separating processes. This is madepossible in that these separating .processes are' carried out bycentrifuging in one and the same centrifuge provided with an additionalinner sieve drum. In this case the separating action can be improvedaccording to the invention by introducing into the inner or outer drumspace, according to the object of theseparation, an assisting agent, forexample a washing out or extracting fluid, steam or gas; A fluid is inthis case preferably squirted into the interior of the inner sieve drumduring the rotation of the drum, in order toemploy forthe separatingprocesses the pressure increase brought about by the centrifugal force.

The steps according to the invention can be employed with advantage forexample in the preparation of clay, in the sugar industry and in thewashing of coal. Particular advantages arise howeverin the manufactureof starch, if according to the invention both the separation of thevegetable fluid from the shreddings of, the initial raw material,especially potatoes, as well as'the separation of the fibrous componentsfrom the 40 starch takes place in one and the same centrifuge. This ispreferably doneby introducing the shreddings of the raw initial materialin dilute form into. the inner rotating sieve drum where it is freedfrom the coarser fibrous constituents, whereupon the starch with thefiner fibrous constituents is separated from the vegetablefluid in theouter rotating drum. Preferably thestarchj is already washed in theinner drum by squirting therein a washing fluid, so that the inner drumboth takes over the role of the usual centrifuge -fed with shreddings,or a corresponding device,

and also replaces the usual following washing-out apparatus,-whilst theouter drum operates in the usual connecting, manner as a milk centrifugeand removes the vegetable fluid, generally completely.

A special milk centrifuge is therefore generally unnecessary. Anyfibrous residues can however still be removed behind the centrifuge, forexample by means of a shaking sieve, whereupon for removing any residualvegetable fluid the starch milk can be introduced again into acentrifuge. For this purpose the outer drum space of a centrifuge havingan additional inner sieve drum is preferably employed, which inner drumserves for the further centrifuging of fibre water resulting from aprevious centrifuge. If this still contains coarse shreddings, these arepreferably further reduced in size prior to introduction into the secondcentrifuge. Accordingly the mesh of the second centrifuge is preferablyfiner than that of the first. Consequently the process according to theinvention may serve, first to separate in one centrifuge coarse pieces,for example shreddings, from finer pieces and then these from a fluid,in order to subject the coarser pieces to a subsequent reduction in sizeand a further corresponding separating process. In both cases, fibrewater or vegetable fluid originating from the centrifuge itself or froma separating device running parallel thereto can be used for dilutingthe shreddings or for washing out purposes in order to economise inwater.

A centrifuge suitable for carrying out the process according to theinvention includes, in a manner known per se, apart from the outer drumprovided in the'usual centrifuges, an additional inner sieve drum, whichcan be set in rotation with a suitable speed of rotation separately fromthe outer drum. The outer drum can be constructed in the same manner asa known sieve drum, but is preferably a centrifuge of usual constructionhaving a closed casing. For carrying out the said process the whole ofthe material to be centrifuged is fed to the inner sieve drum. Contraryto the known centrifuge referred to, the centrifuge according to theinvention is provided with separate outlet conduits for the solidsubstances which deposit on the inner sieve drum and the usual drumrespectively. Preferably feeding devices, which are preferably in theform of discharge worms or the like,and which are driven independentlyof the speed of rotation of the associated drum, are provided for thetwo drum spaces and extend separately up to the associated outletorifices, whilst in the said known centrifuge the discharge conveyorworm of the sieve drum conducts the discharge material to the dischargeworm of the drum having the closed casing.

The outlet orifices of both drum spaces may according to the inventionbe preferably constituted by nozzles rotating with the drums, whichnozzles are preferably arranged tangentially and are in a manner knownper se variable in the cross-section of their outlets in accordance withthe measure of the material undergoing centrifuging. This variation incross-section can be brought about by exchanging the mouth portion ofthe nozzle or by adjusting devices for the cross-section of the outflow,and in such manner that as high a recovery as possible is obtained.

An embodiment of the invention is illustrated by way of example in theaccompanying drawings, in which Fig. lis a central sectional view takenalong the axis of a centrifuge for carrying out the process according tothe invention,

Fig. 2 shows on a larger scale an embodiment of the device for supplyinga washing-out or extracting fluid,

Fig. 3 is a central sectional view along the axis of a modified form ofcarrying out the invention, and

Fig. 4 is an elevational view of this centrifuge seen from the left inFig. 3, partly in section through the sieve drum.

Figure 5 is a fragmentary vertical cross section illustrating atangential nozzle arrangement.

The mixture of solids and fluid to be centrifuged enters the drum spaceformed within the inner additional sieve drum B between the latter andthe central shaft C through the inlets D at one side of the centrifugedrum. This space contains the discharge device for the coarser solidpieces, for example the fibres of the shreddings in the case of starchmanufacture, which cannot pass through the drum B or the materialstretched on it and which upon rotation of the drum B are consequentlydeposited on the inside thereof under the action of centrifugal force.The discharge device consists of the conveyor members 0, which areprovided with inclined scraping heads e which slide along the inner wallof the drum B. Upon rotation-of the hollow shaft C at a rotary velocitydifferent from that of the drum B, the coarser solid substances are inconsequence thereof led by the conveyor members, preferably of a worm,to the outlet orifices (1, since the parts 0 of the conveyor members arerigidly secured in the hollow shaft 0. The openings d feed into anannular space which is provided with outlet nozzles.

Instead of this device other conveying or scraping devices, inparticular worm devices, can be mounted in the interior sieve drumspace. The solid substances issuing from the outlet nozzles G are ingeneral still mixed with a residue of the original fluid, which forexample in the manufacture of starch constitutes with these substancesthe so-called fibre water.

The nozzles F and G preferably are tangentially disposed as shown indetail in Figure 5, and each may include an adjustable lip L and anadjustable wedge W by which movement of the lip can be efiected to varythe cross-sectional area of the nozzle.

The main part of the fluid, which after separation of the coarser solidsubstances now contains only the finer solids, passes through theopenings or pores of the sieve drum or through the material stretchedover it into the outer drum space which is formed by the outer closedhousing A. This is set in rotation in the usual manner, whereupon theheavier solids, for examplc the starch grains of the shredding in starchmanufacture, are deposited towards the drum casing, whilst the fluid,which may still carry the lighter solids, for example finer fibres.passes out of the centrifuge drum through the nozzles F. The solidsdeposited on the closed casing A are brought by a preferably automaticconveyor device, according to Fig. l by a. conveyor worm b, to theoutlet E, through which they leave the centrifuge. The conveyor worm bis preferably connected to the sieve cylinder B, so that" it can bedriven therewith, but it may have a separate driving means, particularlyif it is to be driven at a special velocity. The speed of rotation ofthe worm b must in every case be different from that of the outer drumA.

According to the invention the hollow shaft C itself may be employed asthe inlet for the washing-out fluid, in which case it should be providedwith squirting orifices. In the embodiment i.lustratedhowever thecarriers for the conveyor members care formed hollow, and serve assupply pipes from which an extracting fluid can issue throughsquirtingorifices f. In this case also the hollow shaft, as will be seen at g atthe inlet for the washing-out fluid, serves as a sunply conduit for theorifices f.

For conveying the solid substances separated out at the inner wall ofthe sieve drum to the outlet G, which might also be located on the inletside of the centrifuge, brushes h or rubber strips or the like areprovided as scrapers which rotate with the hollow shaft at a speeddifferent from that of the sieve drum. Since the conveyor members calways wear out in the course of time, their supports may be bent orresilient so that the centrifugal force presses the scraping headsagainst the wall of the sieve. For the same purpose the heads alone mayalso be resiliently mounted on their supports. Together with the sievedrum 13 they constitute a rotating brushing and washing out apparatus.

In order not to interfere with the process of deposition in the outerdrum, when the fluid is thrown by the centrifugal force through thesieve drum, it is advisable to mount on the sieve cylinder, in a mannerknown per se, special guide or run-off plates H in front of the outletorifices for the fluid.

In each of the end walls of the centrifuge special inets may be providedfor one of the drum spaces, for example for the introduction ofvegetable fluid or fibre water in starch manufacture.

For driving the hollow shaft C, the sieve cylinder B and the shell A ofthe drum, there are provided three sets of gear wheels I, II, III. whichare preferably so related that the sieve drum is driven more slowlythanthe shell A but faster than the hollow shaft C, these three partsbeing driven from a common shaft 1. Alternatively the parts A and C mayrotate at the same speed but at a speed different from that of the partB, and may have a corresponding drive.

Differing from the embodiment according to Fig. 1 the sieve drum Bconsists of two sieve cylinders Bi and B2 pushed one into the other andfitting tightly. The apertures h in the non-exchangeable cylinder B1which is rotatably built into the centrifuge have the greatestdimensions which could be required in any case of application of thecentrifuge. The inner sieve cylinder B2 consists of individual arcuatepieces K, which are secured to the outer cylinder by means ofswallow-tail shaped guide strips m. The pieces K are movable in theaxial direction of the centrifuge in these strips, so that they can bepul ed out of or pushed inwards through the openings 21 of the-end wallp of the-outer drum A and the openings q1 of the end wallp1 of the innerdrum B. The apertures l2 of the inner cylinder B2 register completelywith-the apertures h of the cylinder B1 in: the embodiment illustrated,and are of the same size as these. In this case' the sieve drum has thehighest permeability.

If the permeability isv to be reduced, different sieve inserts K havingsmaller apertures l2 can be inserted, which will only permit the passageof correspondingy smaller particles. These apertures is, contrary to thearrangement shown in' the drawings, register only partially with, theapertures l1. The same eifect could be obtained by slightly displacingthe sieve inserts K in an axial direction, until the apertures I: are.

partly covered by solid wall parts of the inserts K.

Those scraping heads e, which are in line in the axial direction are,contrary to the arrangement according to Fig. 1, mounted on a commoncarrier-rail it. These carrier-rails have swallowtail shaped projectionsr, by means of which they can .be pushed axially into correspondinglyshaped recesses in guide members 0. The guide members 0 are secured tothe conveyor arms c at a distance from the central axis which permits ofthe carrier-rails being pulled out or introduced through the openings qand 11. In this manner it is possible to exchange the scraping membersin a series one after the other, without the centrifuge requiring to bedismantled for this purpose.

It is to be understood, of course,

that the openings y will be closed by suitable remcveble cover membersas indicated at Y in Fig ure 3. The exchange is desirable in order to beable to suit the type and nature of the brush heads h to the size of theapertures 12 of the sieve inserts K actually employed and. also onaccountof wear of the brush heads. i

In order to facilitate the reintroduction of material, a cup-like inletmember IM may be affixed to the end of the casing A, as shown in Figures1 and 3, to direct the material through suitable casing end openingsinto the interior of the drum 3 from whence it flows through overflowopenings OF into the surrounding casing A.

The driving mechanism 1, II, III, is for the sake of clearness notillustrated in Fig. 2 but does not interfere with the exchange of thesieve inserts K or of the carrier rails 11, since at least one of theopenings (1 on the side of the driving mechanism opposite the drivingshaft 1' is uncovered.

The squirting of the washing-out agent into the sieve drum can beeffected as in the case of the embodiment shown in Fig. 1 throughopenings j in the conveyor arms 0.

By means of the device described above there 'thereof, means forintroducing into said drum a volume of pulp or fluid from whichsubstance of different particle sizes is to be separated, means forscraping coarse solids from the drum and feeding them toward the coarsesolids discharge outlet, said coniform wall serving to collect heavyfines and direct light fines toward the light fines discharge outlet,means for scraping heavy fines from the wall and feeding them toward theheavy fines discharge outlet, a central shaft on which said coarsesolids scraping means issupported, said heavy fines scraping means beingcarried by said drum, and means for rotating said shaft said drum andsaid wall, said drum being rotated at a speed differing from the speedof rotation of said wall and shaft for rendering said scraping meanseffective.

2.,Apparatus' for the separation of solid constituents of variousparticle size, which are contained in a pulp or in a liquid, from eachother and from the liquid or from the lighter material contained in theliquid, particularly in the manufacture of starch, comprising a rotaryfilter drum, a rotary conical imperforate drum encompassing said firstdrum and rotatable independently thereof, means for supplying all thepulp or liquid to the filter drum, means rotatable relative to,

the filter drum for withdrawing the coarse solid constituents from thefilter drum, means rotatable relative to the imperforate outer drum forwithdrawing heavy solid constituents, which have passed through thefilter drum, at the reduced end of the imperforate outer drum, and meansfor removing the remaining liquid at the other end of the imperforateouter drum, the discharge means on the imperforate outer drum beingindependent of each other and of the discharge means of the filter drum.

3. Apparatus for the separation of solid constituents of variousparticle size, which are contained in a pulp or in a liquid, from eachother and from the liquid or from the lighter material contained in theliquid, particularly in the manufacture of starch, comprising a rotaryfilterdrum,

a rotary conical imperforated drum encompassing said first drum androtatable independently thereof, means for supplying all the pulp orliquid to the filter drum, means rotatable relative to the filter drumfor withdrawing the coarse solid constituents from the filter drum,means rotatable relative to the imperforate outer drum for withdrawingheavy solid constituents, which have passed through the filter drum, atthe reduced end of the imperforate outer drum, means for removing theremaining liquid at the other end of the imperforate outer drum, thedischarge means on the imperforate outer drumbeing independent of eachother and of the discharge means of the filter drum, and means forintroducing a wash-out fluid into said filter drum.

4. Apparatus for the separation of solid constituents of variousparticle size, which are contained in a pulp or in a liquid, from eachother and from the liquid or from the lighter material contained in theliquid, particularly in the manufacture of starch, comprising a rotaryfilter drum,

a rotary conical imperforate drum encompassing said first drum androtatable independently thereof, means for supplying all the pulp orliquid to the filter drum, means rotatable relative to the filter drumfor withdrawing the coarse solid constituents from the filter drum,means rotatable relative to the imperforate outer drum for withdrawingheavy solid constituents, which have passed through the filter drum, atthe reduced end of the imperforate outer drum, and means for removingthe remaining liquid at the other end of the imperforate outer drum, thedischarge means on the imperforate outer drum being independent of eachother and of the discharge means of the filter drum, said means forwithdrawing heavy solid constituents from the filter drum including ahollow shaft portion through which a wash-out fluid is introduced intosaid filter drum.

5. Apparatus for the separation of solid constituents of variousparticle size, which are contained in a pulp or in a liquid, from eachother and from the liquid or from the lighter material contained in theliquid, particularly in the manufacture of starch, comprising a rotaryfilter drum, a rotary conical imperforate drum encompassing said firstdrum and rotatable independently thereof, means for supplying all thepulp or liquid to the filter drum, means rotatable relative to thefilter drum for withdrawing the coarse solid constituents from thefilter drum, means rotatable relative to the imperforate outer drum forwithdrawing heavy solid constituents, which have passed through thefilter drum, at the reduced end of the imperforate outer drum, and meansfor removing the remaining liquid at the other end of the imperforateouter drum, the discharge means on the imperforate outer drum beingindependent of each other and of the discharge means of the filter drum,said means for withdrawing heavy solid constituents from the filter drumincluding filter drum scraping brush elements disposed in angularrelation to the axis of the filter drum, and said means for withdrawingsolid constituents from the imperforate outer drum including a spiralscraper vane carried by the filter drum.

6. An apparatus as defined in claim 2, in which the filter drum includessuperposed shell portions having registering apertures and which arerelatively movable to vary the effective areas of registry of saidapertures to alter the filtering effect of said filter drum. 4

7. An apparatus as defined in claim 2, in which the means forwithdrawing heavy solid constituents from the filter drum includes drumscraping brush elements disposed in angular relation to the axis of thefilter drum and aligned in groups, and bars supporting groups of thebrushes and being removable from the 'filter drums with the groups ofbrush elements thereon.

GEORG J AHIN

